Even if you have a big yard for your kids to play in, flower boxes allow you to bring life to small spaces, such as decks. They're simple to install and easy to care for -- there's no need to kneel to dig in the dirt when you can attach a flower box to your railing. How you attach the box depends on the type of railing you have.
Brackets allow you to easily relocate your flower boxes along your railing without the need for tools. Measure the width of your railing and flower box to determine what size bracket you need. The top section should wrap around the railing and hook underneath, and the bottom section should make a "U" shape so the flower box sets securely in it. These work well for wooden or wrought iron railings. For extra security, use zip ties to hold the brackets in place against the railing. If you're not planning to move the brackets, screwing them into your wooden railing adds security as well.
Clamp brackets typically look similar to the free-hanging brackets, but they include a feature that allows you to secure the brackets onto the railing. The clamp looks like a large, flat-bottom screw. After you place the bracket over the railing, twist the clamp until it presses tightly against the railing and the bracket won't slide to either side. This works with most railing materials, although it can chip paint or leave dents on the underside of the railing if tightened too much. Measure your railing so you know what size clamp to buy.
If you have wooden railings, screws are an option if you don't want to buy separate brackets. Most flower boxes have screw holes already drilled, or they have indented circles to indicate where screws should go. Drill out the screw holes and if necessary, place your flower box on the railing and mark the location of the holes on the railing. Remove the box and drill starter holes into the wood, and then put your flower box back in place and screw it tightly to the railing. This is best for small flower boxes; large ones are heavy when filled with soil and plants, and without the bottom support of a bracket, they might not stay securely screwed into the railing.
Instead of hanging flower baskets over the side of your railing, choose saddle-style planters that set on top of your railing. These have flower boxes on both sides with a flat connector in the middle. Choose one that has a connector slightly wider than your railing so you can easily slide it over the top. No screws are required with most saddle flower boxes, but some have screw holes in the connector in case you want to attach the box more securely.